Global distribution of two fungal pathogens threatening endangered sea turtles

This work was supported by grants of Ministerio de Ciencia e Innovación, Spain (CGL2009-10032, CGL2012-32934). J.M.S.R was supported by PhD fellowship of the CSIC (JAEPre 0901804). The Natural Environment Research Council and the Biotechnology and Biological Sciences Research Council supported P.V.W. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. Thanks Machalilla National Park in Ecuador, Pacuare Nature Reserve in Costa Rica, Foundations Natura 2000 in Cape Verde and Equilibrio Azul in Ecuador, Dr. Jesus Muñoz, Dr. Ian Bell, Dr. Juan Patiño for help and technical support during samplingPeer reviewedPublisher PD

Beyond sea turtles: Fusarium keratoplasticum in eggshells of podocnemis unifilis, a threatened amazonian freshwater turtle

The endangered yellow-spotted river turtle (Podocnemis unifilis) has experienced a dramatic population decline in the Ecuadorian Amazonia, mainly due to overexploitation of its eggs. To reverse this trend, the Wildlife Conservation Society has developed a head-start program in Yasuní National Park since 2008, but the potential risk that microbes associated with its eggs might represent for hatching success has not been evaluated yet. Members of the Fusarium solani species complex (FSSC) are involved in egg failure in sea turtles under natural and hatchery conditions, but their role in infecting the eggs of P. unifilis is unknown. In this study, we collected eggshells of P. unifilis and obtained 50 fungal and bacterial isolates. Some potentially pathogenic fungi of the genera Fusarium, Penicillium and Rhizopus were identified based on molecular data. Most importantly, the sea turtle pathogenic species F. keratoplasticum not only was present, but it was the most frequently found. Conversely, we have also isolated other microorganisms, such as Pseudomonas or Phoma-like species, producing a wide spectrum of antifungal compounds that may have a protective role against fungal diseases. Our survey provides useful information on potential pathogens found in P. unifilis eggshells, upon which the success of conservation programs may depend.This research was funded by the Real Jardín Botánico (Spanish National Research Council, CSIC), and the MS program “Biodiversity and its Conservation in Tropical Areas” of the Menéndez Pelayo International University-CSIC

Unraveling the ecology and epidemiology of an emerging fungal disease, sea turtle egg fusariosis (STEF)

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Composition of the microbial community of shells of <i>Fusarium</i>-infected eggs detected by the PhyloChip analysis.

<p>A) Number of OTUs per phylum detected on hatched (H) and unhatched (UH) eggshells collected from two nests (numbers 1 and 2). Values with >0.25% of occurrence. B) Average distribution of OTUs for all the samples (<i>n</i> = 4).</p

16S rDNA sequence identities of the Actinobacteria, isolated from sea turtle eggshells, that inhibited the hyphal growth of <i>Fusarium falciforme</i>.

a<p>ACT corresponds to the acronym of the Actinobacterial isolates.</p>b<p>BLAST hit corresponds to the Greengenes database (greengenes.lbl.gov/cgi-bin/nph-blast_interface.cgi).</p><p>The data represent the best BLAST hit with 16S rDNA sequences from the GreenGenes database (greengenes.lbl.gov/cgi-bin/nph-blast_interface.cgi).</p

Fusarium solani is responsible for mass mortalities in nests of loggerhead sea turtle, Caretta caretta, in Boavista, Cape Verde

The fungus Fusarium solani (Mart.) Saccardo (1881) was found to be the cause of infections in the eggs of the sea turtle species Caretta caretta in Boavista Island, Cape Verde. Egg shells with early and severe symptoms of infection, as well as diseased embryos were sampled from infected nests. Twenty-five isolates with similar morphological characteristics were obtained. Their ITS rRNA gene sequences were similar to the GenBank sequences corresponding to F. solani and their maximum identity ranged from 95% to 100%. Phylogenetic parsimony and Bayesian analyses of these isolates showed that they belong to a single F. solani clade and that they are distributed in two subclades named A and C (the latter containing 23 out of 25). A representative isolate of subclade C was used in challenge inoculation experiments to test Koch postulates. Mortality rates were c. 83.3% in challenged eggs and 8.3% in the control. Inoculated challenged eggs exhibited the same symptoms as infected eggs found in the field. Thus, this work demonstrates that a group of strains of F. solani are responsible for the symptoms observed on turtle-nesting beaches, and that they represent a risk for the survival of this endangered speciesPeer reviewe

Mean optimal growth temperature (OGT) of <i>Fusarium</i> isolates.

<p>The OGT was calculated for selected isolates from the sea turtle pathogenic species clustered in subclades A (<i>Fusarium falciforme</i>) and C (<i>Fusarium keratoplasticum</i>) and non- sea turtle isolates clustered in subclade B, within the <i>Fusarium solani</i> species complex. Differences in OGT for each group of isolates were determined by one-way ANOVA followed by a <i>post-hoc</i> Tukey HSD test. Data represent mean ± standard error bars (s.e.m) of three independent experiments.</p

Bootstrapped multilocus out-group-rooted cladogram.

<p>Summarized cladogram of the <i>Fusarium solani</i> species complex inferred from the DNA regions: ITS nrDNA, LSU nrDNA and <i>RPB2</i>. Thick branches correspond to highly supported groups, <i>i.e.</i>, posterior probability (PP) and the bootstrap values (BS) of the parsimony and Bayesian analysis when PP≥0.95 and BS≥70. The sea turtle isolates are highlighted in bold. A solid asterisk to the right of an NRRL number identifies the <i>F. falciforme</i> isolates. A solid rectangle to the right of an NRRL number identifies <i>F. keratoplasticum</i> isolates. For full details of three, see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0085853#pone.0085853.s002" target="_blank">Figure S2</a>.</p